// Package tests contains the end-to-end API suite.
//
// These are true integration tests: every request travels over HTTP to a live
// server, every assertion inspects the real filesystem. There are no mocks, no
// fakes and no in-memory doubles anywhere in this file -- if the flat-file engine
// breaks, these tests break.
package tests

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"

	"go-doc/router"
	"go-doc/storage"
)

// harness wires a real storage engine to a real HTTP server over a temporary
// data directory.
type harness struct {
	t        *testing.T
	dataDir  string
	engine   *storage.Engine
	server   *httptest.Server
	client   *http.Client
	docsDir  string
	notePath string
}

func newHarness(t *testing.T) *harness {
	t.Helper()

	dataDir := t.TempDir()
	engine, err := storage.New(dataDir)
	if err != nil {
		t.Fatalf("integration: provision engine: %v", err)
	}

	handler, err := router.NewWithConfig(router.Config{
		Engine: engine,
		Logger: discardLogger(),
	})
	if err != nil {
		t.Fatalf("integration: build router: %v", err)
	}

	server := httptest.NewServer(handler)
	t.Cleanup(server.Close)

	return &harness{
		t:        t,
		dataDir:  dataDir,
		engine:   engine,
		server:   server,
		client:   server.Client(),
		docsDir:  filepath.Join(dataDir, "docs"),
		notePath: filepath.Join(dataDir, "comments"),
	}
}

// request performs an HTTP call and returns the response with its body.
func (h *harness) request(method, path, contentType, body string) (*http.Response, []byte) {
	h.t.Helper()

	var reader io.Reader
	if body != "" {
		reader = strings.NewReader(body)
	}
	req, err := http.NewRequest(method, h.server.URL+path, reader)
	if err != nil {
		h.t.Fatalf("integration: build %s %s: %v", method, path, err)
	}
	if contentType != "" {
		req.Header.Set("Content-Type", contentType)
	}

	resp, err := h.client.Do(req)
	if err != nil {
		h.t.Fatalf("integration: %s %s: %v", method, path, err)
	}
	defer resp.Body.Close()

	payload, err := io.ReadAll(resp.Body)
	if err != nil {
		h.t.Fatalf("integration: read body of %s %s: %v", method, path, err)
	}
	return resp, payload
}

func (h *harness) expectStatus(method, path, contentType, body string, want int) []byte {
	h.t.Helper()
	resp, payload := h.request(method, path, contentType, body)
	if resp.StatusCode != want {
		h.t.Fatalf("%s %s: expected HTTP %d, got %d (body: %s)", method, path, want, resp.StatusCode, payload)
	}
	return payload
}

func decodeJSON[T any](t *testing.T, payload []byte) T {
	t.Helper()
	var out T
	if err := json.Unmarshal(payload, &out); err != nil {
		t.Fatalf("integration: decode %s: %v", payload, err)
	}
	return out
}

// requireFile asserts a file exists on the real filesystem and returns its bytes.
func requireFile(t *testing.T, path string) []byte {
	t.Helper()
	data, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("integration: expected %s to exist: %v", path, err)
	}
	return data
}

func requireNoFile(t *testing.T, path string) {
	t.Helper()
	if _, err := os.Stat(path); err == nil {
		t.Fatalf("integration: expected %s to be absent", path)
	} else if !os.IsNotExist(err) {
		t.Fatalf("integration: stat %s: %v", path, err)
	}
}

// ---------------------------------------------------------------------------
// TestIntegrationDocumentLifecycle
// ---------------------------------------------------------------------------

func TestIntegrationDocumentLifecycle(t *testing.T) {
	t.Parallel()
	h := newHarness(t)

	t.Run("health reports the live data root", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/health", "", "", http.StatusOK)
		health := decodeJSON[struct {
			Status   string `json:"status"`
			DataRoot string `json:"data_root"`
		}](t, payload)

		if health.Status != "ok" {
			t.Fatalf("expected status ok, got %q", health.Status)
		}
		if health.DataRoot != h.dataDir {
			t.Fatalf("expected data root %q, got %q", h.dataDir, health.DataRoot)
		}
	})

	t.Run("POST creates a slugified Markdown file on disk", func(t *testing.T) {
		payload := h.expectStatus(
			"POST", "/api/docs/Core%20Service%20API", "text/markdown",
			"# Core Service API\n\nBilling and invoicing endpoints.\n",
			http.StatusCreated,
		)
		saved := decodeJSON[struct {
			Slug    string `json:"slug"`
			Title   string `json:"title"`
			Created bool   `json:"created"`
		}](t, payload)

		if saved.Slug != "core-service-api" {
			t.Fatalf("expected slug core-service-api, got %q", saved.Slug)
		}
		if !saved.Created {
			t.Fatal("expected created=true on first write")
		}
		if saved.Title != "Core Service API" {
			t.Fatalf("expected the H1 to become the title, got %q", saved.Title)
		}

		onDisk := requireFile(t, filepath.Join(h.docsDir, "core-service-api.md"))
		if !bytes.Contains(onDisk, []byte("Billing and invoicing endpoints.")) {
			t.Fatalf("file content mismatch: %s", onDisk)
		}
	})

	t.Run("GET returns the raw Markdown with the right content type", func(t *testing.T) {
		resp, payload := h.request("GET", "/api/docs/core-service-api", "", "")
		if resp.StatusCode != http.StatusOK {
			t.Fatalf("expected 200, got %d", resp.StatusCode)
		}
		if ct := resp.Header.Get("Content-Type"); !strings.HasPrefix(ct, "text/markdown") {
			t.Fatalf("expected text/markdown, got %q", ct)
		}
		if !strings.HasPrefix(string(payload), "# Core Service API") {
			t.Fatalf("unexpected markdown body: %s", payload)
		}
	})

	t.Run("GET ?format=json returns the document envelope", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/docs/core-service-api?format=json", "", "", http.StatusOK)
		doc := decodeJSON[struct {
			Slug    string `json:"slug"`
			Title   string `json:"title"`
			Content string `json:"content"`
			Size    int64  `json:"size"`
		}](t, payload)

		if doc.Slug != "core-service-api" || doc.Title != "Core Service API" {
			t.Fatalf("unexpected envelope: %+v", doc)
		}
		if doc.Size <= 0 {
			t.Fatalf("expected a positive size, got %d", doc.Size)
		}
	})

	t.Run("POST with a JSON body updates the file in place", func(t *testing.T) {
		h.expectStatus(
			"POST", "/api/docs/core-service-api", "application/json",
			`{"title":"Core Service API v2","content":"# Core Service API v2\n\nRewritten.\n"}`,
			http.StatusOK,
		)

		onDisk := string(requireFile(t, filepath.Join(h.docsDir, "core-service-api.md")))
		if strings.Contains(onDisk, "Billing and invoicing") {
			t.Fatalf("update did not replace the content wholesale: %s", onDisk)
		}
		if !strings.Contains(onDisk, "# Core Service API v2") {
			t.Fatalf("update missing from disk: %s", onDisk)
		}
	})

	t.Run("GET /api/docs indexes the document", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/docs", "", "", http.StatusOK)
		index := decodeJSON[struct {
			Count int               `json:"count"`
			Docs  []storage.DocMeta `json:"docs"`
		}](t, payload)

		if index.Count != 1 || index.Docs[0].Slug != "core-service-api" {
			t.Fatalf("unexpected index: %+v", index)
		}
	})

	t.Run("search filters the index", func(t *testing.T) {
		h.expectStatus("POST", "/api/docs/Payments%20Gateway", "text/markdown", "# Payments Gateway\n", http.StatusCreated)

		payload := h.expectStatus("GET", "/api/docs?q=payment", "", "", http.StatusOK)
		index := decodeJSON[struct {
			Count int `json:"count"`
		}](t, payload)
		if index.Count != 1 {
			t.Fatalf("expected exactly one search hit, got %d", index.Count)
		}

		payload = h.expectStatus("GET", "/api/docs?q=nothing-matches", "", "", http.StatusOK)
		index = decodeJSON[struct {
			Count int `json:"count"`
		}](t, payload)
		if index.Count != 0 {
			t.Fatalf("expected no hits, got %d", index.Count)
		}
	})

	t.Run("DELETE removes the file and cascades the feedback", func(t *testing.T) {
		h.expectStatus("POST", "/api/docs/core-service-api/comments", "application/json",
			`{"author":"ana","role":"developer","content":"delete me"}`, http.StatusCreated)
		requireFile(t, filepath.Join(h.notePath, "core-service-api-comments.json"))

		h.expectStatus("DELETE", "/api/docs/core-service-api", "", "", http.StatusNoContent)
		requireNoFile(t, filepath.Join(h.docsDir, "core-service-api.md"))
		requireNoFile(t, filepath.Join(h.notePath, "core-service-api-comments.json"))

		h.expectStatus("GET", "/api/docs/core-service-api", "", "", http.StatusNotFound)
		h.expectStatus("DELETE", "/api/docs/core-service-api", "", "", http.StatusNotFound)
	})
}

// ---------------------------------------------------------------------------
// TestIntegrationCommentTracking
// ---------------------------------------------------------------------------

func TestIntegrationCommentTracking(t *testing.T) {
	t.Parallel()
	h := newHarness(t)

	h.expectStatus("POST", "/api/docs/Deploy%20Pipeline", "text/markdown", "# Deploy Pipeline\n", http.StatusCreated)

	type created struct {
		Comment storage.Comment `json:"comment"`
		Badge   string          `json:"badge"`
	}

	cases := []struct {
		role    string
		author  string
		content string
		badge   string
	}{
		{"user", "sam", "The wizard confused me", "🟢"},
		{"Operator", "robin", "Rollback takes 20 minutes", "🔵"},
		{"DEVELOPER", "kit", "Add a --dry-run flag", "🔴"},
	}

	for _, tc := range cases {
		t.Run("role "+tc.role+" receives badge "+tc.badge, func(t *testing.T) {
			body := fmt.Sprintf(`{"author":%q,"role":%q,"content":%q}`, tc.author, tc.role, tc.content)
			payload := h.expectStatus("POST", "/api/docs/deploy-pipeline/comments", "application/json", body, http.StatusCreated)
			result := decodeJSON[created](t, payload)

			if result.Badge != tc.badge {
				t.Fatalf("expected badge %q, got %q", tc.badge, result.Badge)
			}
			if result.Comment.Badge != tc.badge {
				t.Fatalf("expected the stored badge %q, got %q", tc.badge, result.Comment.Badge)
			}
			if result.Comment.ID == "" {
				t.Fatal("expected a generated comment ID")
			}
			if result.Comment.Timestamp.IsZero() {
				t.Fatal("expected a timestamp")
			}
			if string(result.Comment.Role) != strings.ToLower(tc.role) {
				t.Fatalf("expected the canonical role, got %q", result.Comment.Role)
			}
		})
	}

	t.Run("the feedback file is a JSON array in insertion order", func(t *testing.T) {
		raw := requireFile(t, filepath.Join(h.notePath, "deploy-pipeline-comments.json"))
		if !strings.HasPrefix(strings.TrimSpace(string(raw)), "[") {
			t.Fatalf("expected a JSON array, got: %s", raw)
		}

		var stored []storage.Comment
		if err := json.Unmarshal(raw, &stored); err != nil {
			t.Fatalf("feedback file is not valid JSON: %v", err)
		}
		if len(stored) != 3 {
			t.Fatalf("expected 3 comments, got %d", len(stored))
		}
		for i, want := range []struct{ role, badge string }{
			{"user", "🟢"},
			{"operator", "🔵"},
			{"developer", "🔴"},
		} {
			if string(stored[i].Role) != want.role || stored[i].Badge != want.badge {
				t.Fatalf("comment %d: got %s/%s, want %s/%s", i, stored[i].Role, stored[i].Badge, want.role, want.badge)
			}
		}
	})

	t.Run("GET lists the comments with their badges", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/docs/deploy-pipeline/comments", "", "", http.StatusOK)
		listed := decodeJSON[struct {
			Comments []storage.Comment `json:"comments"`
			Count    int               `json:"count"`
		}](t, payload)

		if listed.Count != 3 || len(listed.Comments) != 3 {
			t.Fatalf("expected 3 comments, got %d", listed.Count)
		}
		if listed.Comments[2].Badge != "🔴" {
			t.Fatalf("expected the developer badge, got %q", listed.Comments[2].Badge)
		}
	})

	t.Run("DELETE removes a single comment by ID", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/docs/deploy-pipeline/comments", "", "", http.StatusOK)
		listed := decodeJSON[struct {
			Comments []storage.Comment `json:"comments"`
		}](t, payload)

		target := listed.Comments[0].ID
		h.expectStatus("DELETE", "/api/docs/deploy-pipeline/comments/"+target, "", "", http.StatusNoContent)
		h.expectStatus("DELETE", "/api/docs/deploy-pipeline/comments/"+target, "", "", http.StatusNotFound)

		remaining := decodeJSON[struct {
			Count int `json:"count"`
		}](t, h.expectStatus("GET", "/api/docs/deploy-pipeline/comments", "", "", http.StatusOK))
		if remaining.Count != 2 {
			t.Fatalf("expected 2 remaining comments, got %d", remaining.Count)
		}
	})

	t.Run("stats aggregate by role", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/docs/deploy-pipeline/stats", "", "", http.StatusOK)
		stats := decodeJSON[storage.CommentStats](t, payload)

		if stats.Total != 2 {
			t.Fatalf("expected total 2, got %d", stats.Total)
		}
		if stats.ByRole["operator"] != 1 || stats.ByRole["developer"] != 1 {
			t.Fatalf("unexpected role tally: %+v", stats.ByRole)
		}
	})

	t.Run("the role catalogue is exposed for the UI", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/roles", "", "", http.StatusOK)
		catalogue := decodeJSON[struct {
			Roles []struct {
				Role  string `json:"role"`
				Badge string `json:"badge"`
				Label string `json:"label"`
				Hex   string `json:"hex"`
			} `json:"roles"`
		}](t, payload)

		want := map[string][3]string{
			"user":      {"🟢", "User", "#22c55e"},
			"operator":  {"🔵", "Operator", "#3b82f6"},
			"developer": {"🔴", "Developer", "#ef4444"},
		}
		if len(catalogue.Roles) != 3 {
			t.Fatalf("expected 3 roles, got %d", len(catalogue.Roles))
		}
		for _, role := range catalogue.Roles {
			expected, ok := want[role.Role]
			if !ok {
				t.Fatalf("unexpected role %q", role.Role)
			}
			if role.Badge != expected[0] || role.Label != expected[1] || role.Hex != expected[2] {
				t.Fatalf("role %s mismatch: %+v", role.Role, role)
			}
		}
	})
}

// ---------------------------------------------------------------------------
// TestIntegrationValidationAndErrors
// ---------------------------------------------------------------------------

func TestIntegrationValidationAndErrors(t *testing.T) {
	t.Parallel()
	h := newHarness(t)

	t.Run("unknown document returns a structured 404", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/docs/does-not-exist", "", "", http.StatusNotFound)
		body := decodeJSON[struct {
			Error struct {
				Code    string `json:"code"`
				Message string `json:"message"`
			} `json:"error"`
			Status int `json:"status"`
		}](t, payload)

		if body.Error.Code != "not_found" || body.Status != http.StatusNotFound {
			t.Fatalf("unexpected error body: %s", payload)
		}
	})

	t.Run("invalid role returns 400 invalid_role", func(t *testing.T) {
		h.expectStatus("POST", "/api/docs/guarded", "text/markdown", "# Guarded\n", http.StatusCreated)
		payload := h.expectStatus("POST", "/api/docs/guarded/comments", "application/json",
			`{"author":"mallory","role":"root","content":"escalate"}`, http.StatusBadRequest)

		if !strings.Contains(string(payload), "invalid_role") {
			t.Fatalf("expected invalid_role, got %s", payload)
		}
		requireNoFile(t, filepath.Join(h.notePath, "guarded-comments.json"))
	})

	t.Run("empty comment content returns 400 invalid_comment", func(t *testing.T) {
		payload := h.expectStatus("POST", "/api/docs/guarded/comments", "application/json",
			`{"author":"ana","role":"user","content":"   "}`, http.StatusBadRequest)
		if !strings.Contains(string(payload), "invalid_comment") {
			t.Fatalf("expected invalid_comment, got %s", payload)
		}
	})

	t.Run("malformed JSON returns 400 invalid_body", func(t *testing.T) {
		payload := h.expectStatus("POST", "/api/docs/guarded/comments", "application/json", `{"author":`, http.StatusBadRequest)
		if !strings.Contains(string(payload), "invalid_body") {
			t.Fatalf("expected invalid_body, got %s", payload)
		}
	})

	t.Run("traversal slugs are refused", func(t *testing.T) {
		for _, path := range []string{
			"/api/docs/..%2F..%2Fetc%2Fpasswd",
			"/api/docs/%2Fetc%2Fpasswd",
		} {
			h.expectStatus("POST", path, "text/markdown", "nope", http.StatusBadRequest)
		}
	})

	t.Run("oversized documents are refused", func(t *testing.T) {
		huge := strings.Repeat("a", int(router.DefaultMaxDocBytes)+1024)
		h.expectStatus("POST", "/api/docs/huge", "text/markdown", huge, http.StatusBadRequest)
		requireNoFile(t, filepath.Join(h.docsDir, "huge.md"))
	})

	t.Run("unknown API routes return JSON 404, not an HTML page", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/nope", "", "", http.StatusNotFound)
		if !strings.Contains(string(payload), "not_found") {
			t.Fatalf("expected a JSON error, got %s", payload)
		}
	})
}

// ---------------------------------------------------------------------------
// TestIntegrationCORS
// ---------------------------------------------------------------------------

func TestIntegrationCORS(t *testing.T) {
	t.Parallel()
	h := newHarness(t)

	t.Run("preflight is answered for the Vite dev server", func(t *testing.T) {
		resp, _ := h.request("OPTIONS", "/api/docs/core-service-api", "", "")
		if resp.StatusCode != http.StatusNoContent {
			t.Fatalf("expected 204, got %d", resp.StatusCode)
		}
		if origin := resp.Header.Get("Access-Control-Allow-Origin"); origin != "*" {
			t.Fatalf("expected a wildcard origin, got %q", origin)
		}
		methods := resp.Header.Get("Access-Control-Allow-Methods")
		for _, verb := range []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"} {
			if !strings.Contains(methods, verb) {
				t.Fatalf("expected %s in %q", verb, methods)
			}
		}
		if headers := resp.Header.Get("Access-Control-Allow-Headers"); !strings.Contains(headers, "Content-Type") {
			t.Fatalf("expected Content-Type to be allowed, got %q", headers)
		}
	})

	t.Run("cross-origin reads carry the CORS header", func(t *testing.T) {
		req, err := http.NewRequest("GET", h.server.URL+"/api/docs", nil)
		if err != nil {
			t.Fatal(err)
		}
		req.Header.Set("Origin", "http://127.0.0.1:5173")

		resp, err := h.client.Do(req)
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()

		if origin := resp.Header.Get("Access-Control-Allow-Origin"); origin != "*" {
			t.Fatalf("expected a CORS header, got %q", origin)
		}
	})

	t.Run("an allow-list echoes only permitted origins", func(t *testing.T) {
		dataDir := t.TempDir()
		engine, err := storage.New(dataDir)
		if err != nil {
			t.Fatal(err)
		}
		handler, err := router.NewWithConfig(router.Config{
			Engine:         engine,
			AllowedOrigins: []string{"http://127.0.0.1:5173"},
			Logger:         discardLogger(),
		})
		if err != nil {
			t.Fatal(err)
		}
		server := httptest.NewServer(handler)
		defer server.Close()

		for origin, wantEchoed := range map[string]bool{
			"http://127.0.0.1:5173":   true,
			"http://evil.example.com": false,
		} {
			req, err := http.NewRequest("GET", server.URL+"/api/health", nil)
			if err != nil {
				t.Fatal(err)
			}
			req.Header.Set("Origin", origin)

			resp, err := server.Client().Do(req)
			if err != nil {
				t.Fatal(err)
			}
			resp.Body.Close()

			got := resp.Header.Get("Access-Control-Allow-Origin")
			if wantEchoed && got != origin {
				t.Fatalf("expected %q to be echoed, got %q", origin, got)
			}
			if !wantEchoed && got == origin {
				t.Fatalf("origin %q should not have been echoed", origin)
			}
		}
	})
}

// ---------------------------------------------------------------------------
// TestIntegrationConcurrentLoad
// ---------------------------------------------------------------------------

func TestIntegrationConcurrentLoad(t *testing.T) {
	t.Parallel()
	h := newHarness(t)

	const (
		docs          = 40
		perDoc        = 30
		commentsTotal = docs * perDoc
	)

	t.Run("concurrent writers all land on disk", func(t *testing.T) {
		var wg sync.WaitGroup
		errs := make(chan error, docs)

		for d := 0; d < docs; d++ {
			wg.Add(1)
			go func(index int) {
				defer wg.Done()
				title := fmt.Sprintf("Load Service %02d", index)
				body := fmt.Sprintf("# %s\n\n## For Users\n\nUsage.\n\n## For Operators\n\nRunbook.\n\n## For Developers\n\nAPI.\n", title)

				resp, payload := h.request("POST", "/api/docs/"+storage.Slugify(title), "text/markdown", body)
				if resp.StatusCode != http.StatusCreated && resp.StatusCode != http.StatusOK {
					errs <- fmt.Errorf("save %s returned %d: %s", title, resp.StatusCode, payload)
					return
				}

				for n := 0; n < perDoc; n++ {
					role := []string{"user", "operator", "developer"}[n%3]
					comment := fmt.Sprintf(
						`{"author":"load-%02d","role":%q,"content":"comment %d"}`, index, role, n)
					resp, payload := h.request("POST", "/api/docs/"+storage.Slugify(title)+"/comments", "application/json", comment)
					if resp.StatusCode != http.StatusCreated {
						errs <- fmt.Errorf("comment on %s returned %d: %s", title, resp.StatusCode, payload)
						return
					}
				}
			}(d)
		}

		wg.Wait()
		close(errs)
		for err := range errs {
			t.Fatal(err)
		}
	})

	t.Run("the filesystem holds every document", func(t *testing.T) {
		entries, err := os.ReadDir(h.docsDir)
		if err != nil {
			t.Fatal(err)
		}
		if len(entries) != docs {
			t.Fatalf("expected %d Markdown files, got %d", docs, len(entries))
		}
	})

	t.Run("the filesystem holds every comment", func(t *testing.T) {
		entries, err := os.ReadDir(h.notePath)
		if err != nil {
			t.Fatal(err)
		}
		if len(entries) != docs {
			t.Fatalf("expected %d feedback files, got %d", docs, len(entries))
		}

		total := 0
		for _, entry := range entries {
			raw, err := os.ReadFile(filepath.Join(h.notePath, entry.Name()))
			if err != nil {
				t.Fatal(err)
			}
			var stored []storage.Comment
			if err := json.Unmarshal(raw, &stored); err != nil {
				t.Fatalf("%s is not a valid JSON array: %v", entry.Name(), err)
			}
			total += len(stored)
		}
		if total != commentsTotal {
			t.Fatalf("expected %d comments across all files, got %d", commentsTotal, total)
		}
	})

	t.Run("the API agrees with the filesystem", func(t *testing.T) {
		payload := h.expectStatus("GET", "/api/stats", "", "", http.StatusOK)
		stats := decodeJSON[struct {
			Docs     int `json:"docs"`
			Comments int `json:"comments"`
		}](t, payload)

		if stats.Docs != docs {
			t.Fatalf("expected %d docs, got %d", docs, stats.Docs)
		}
		if stats.Comments != commentsTotal {
			t.Fatalf("expected %d comments, got %d", commentsTotal, stats.Comments)
		}
	})

	t.Run("no temp files leaked and every comment is badged", func(t *testing.T) {
		entries, err := os.ReadDir(h.docsDir)
		if err != nil {
			t.Fatal(err)
		}
		for _, entry := range entries {
			if strings.HasPrefix(entry.Name(), ".godoc-tmp-") {
				t.Fatalf("leaked atomic-write temp file: %s", entry.Name())
			}
		}

		for d := 0; d < docs; d++ {
			slug := storage.Slugify(fmt.Sprintf("Load Service %02d", d))
			raw := requireFile(t, filepath.Join(h.notePath, slug+"-comments.json"))
			var stored []storage.Comment
			if err := json.Unmarshal(raw, &stored); err != nil {
				t.Fatal(err)
			}
			if len(stored) != perDoc {
				t.Fatalf("%s: expected %d comments, got %d", slug, perDoc, len(stored))
			}
			for _, comment := range stored {
				if comment.Badge != comment.Role.Badge() {
					t.Fatalf("%s: comment %s has badge %q for role %s", slug, comment.ID, comment.Badge, comment.Role)
				}
			}
		}
	})
}

// ---------------------------------------------------------------------------
// TestIntegrationPersistenceAcrossRestart
// ---------------------------------------------------------------------------

func TestIntegrationPersistenceAcrossRestart(t *testing.T) {
	t.Parallel()

	dataDir := t.TempDir()

	// First "process": write through the API.
	engine, err := storage.New(dataDir)
	if err != nil {
		t.Fatal(err)
	}
	handler, err := router.NewWithConfig(router.Config{Engine: engine, Logger: discardLogger()})
	if err != nil {
		t.Fatal(err)
	}
	first := httptest.NewServer(handler)

	post := func(method, path, contentType, body string) []byte {
		t.Helper()
		req, err := http.NewRequest(method, first.URL+path, strings.NewReader(body))
		if err != nil {
			t.Fatal(err)
		}
		req.Header.Set("Content-Type", contentType)
		resp, err := first.Client().Do(req)
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()
		payload, _ := io.ReadAll(resp.Body)
		if resp.StatusCode >= 300 {
			t.Fatalf("%s %s returned %d: %s", method, path, resp.StatusCode, payload)
		}
		return payload
	}

	post("POST", "/api/docs/Persistent%20Store", "text/markdown", "# Persistent Store\n\nSurvives restarts.\n")
	post("POST", "/api/docs/persistent-store/comments", "application/json",
		`{"author":"ana","role":"developer","content":"still here after a restart"}`)
	first.Close()

	// Second "process": a brand new engine over the same directory.
	restarted, err := storage.New(dataDir)
	if err != nil {
		t.Fatal(err)
	}
	handler, err = router.NewWithConfig(router.Config{Engine: restarted, Logger: discardLogger()})
	if err != nil {
		t.Fatal(err)
	}
	second := httptest.NewServer(handler)
	defer second.Close()

	t.Run("the document survives", func(t *testing.T) {
		resp, err := second.Client().Get(second.URL + "/api/docs/persistent-store?format=json")
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()

		doc := decodeJSON[struct {
			Title   string `json:"title"`
			Content string `json:"content"`
		}](t, mustReadAll(resp))

		if doc.Title != "Persistent Store" {
			t.Fatalf("unexpected title %q", doc.Title)
		}
		if !strings.Contains(doc.Content, "Survives restarts.") {
			t.Fatalf("unexpected content %q", doc.Content)
		}
	})

	t.Run("the feedback survives with its badge", func(t *testing.T) {
		resp, err := second.Client().Get(second.URL + "/api/docs/persistent-store/comments")
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()

		listed := decodeJSON[struct {
			Count    int               `json:"count"`
			Comments []storage.Comment `json:"comments"`
		}](t, mustReadAll(resp))

		if listed.Count != 1 {
			t.Fatalf("expected 1 comment, got %d", listed.Count)
		}
		if listed.Comments[0].Badge != "🔴" {
			t.Fatalf("expected the developer badge, got %q", listed.Comments[0].Badge)
		}
	})
}

func mustReadAll(resp *http.Response) []byte {
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		panic(err)
	}
	return data
}

func TestIntegrationTimingBudget(t *testing.T) {
	t.Parallel()
	h := newHarness(t)

	start := time.Now()
	h.expectStatus("POST", "/api/docs/timing", "text/markdown", strings.Repeat("Line of content.\n\n", 500), http.StatusCreated)
	for i := 0; i < 100; i++ {
		h.expectStatus("POST", "/api/docs/timing/comments", "application/json",
			fmt.Sprintf(`{"author":"bench","role":"user","content":"note %d"}`, i), http.StatusCreated)
	}
	h.expectStatus("GET", "/api/docs/timing", "", "", http.StatusOK)

	if elapsed := time.Since(start); elapsed > 30*time.Second {
		t.Fatalf("write path took %s, which is far too slow for a flat-file engine", elapsed)
	}
}